Pyridine glycols and process of making them



PYRIDINE GLYCOLS AND PRUCESS MAKING THEM Francis E. Cislak, Indianapolis, Ind, assigrior to Reiiiy Tar'& Chemical Corporation, Indianapoiis, ind, enrporation of Indiana No Drawing. Application September 1, 1954,

Serial No. 453,688

Claims, g1. m 297 This invention relates to pyridine glycols and to the process of preparing them. More particularly, it relates to 2-pyridylglycols and to 4-pyridylglycols which com pounds may be represented by'the following formulae:

Where n is l to 3 and R and R are hydrogen or alkyl.

The pyridylglycols of my invention are useful in the cQoHmorr manufacture of certain types of synthetic fibers. One of the newer and more acceptable synthetic fibers, Dacron, is a polyester or" terephthalic acid and ethyleneglycol. The dyeing of Dacron type fibers has not heretofore been solved. Attempts have been made to achieve the penetration of the closely packed molecular chains by the use of carriers, by dyeing at high temperaturea or by forming the final dye molecule within the fiber. By the use of. a small percentage (3% to 7%) of pyridylglycols in the molecular make-up of the polyesters, the dyeing properties are greatly enhanced. The presence of the pyridine ring nitrogen in the resin molecule furnishes a point of attachment for acid dyes, thereby enabling the fibers to be dyed in the usual manner. The degree of the dye absorption depends upon the number of pyridine ring nitrogens present in the resin molecule.

In recent years several polyester resins have achieved industrial stature. Noteworthy 'is the use of glass fiber reinforced polyesters for the manufacture of automobile bodies. It is recognized that the usefulness of the resins in automobile bodies depends upon the ability to bond the glass fiber reinforcement to the polyester resin. The in corporation of pyridylglycols into the molecular make-up of the polyester resins increases the bond of the resins to the glass fibers.

A pyridyl glycol, 2-(2-pyridyl)propandiol 1:3, may be formed by the condensation of '2 pico1ine with formaldehyde. The yield of this glycol. is very small, the main product of the reaction is Z-pyridyletl ian ol. Attempts to increase the yield of the glycol have invariably resulted in the formation of a tarry mass instead of'tl e desired 2- pyridylpropandiol 1:3.

While I have not succeeded in improving the process of making 2-(2-pyridyl)propandio1 1:3, I have discovered a way of preparing 1-(2-pyridyl)propandiol 1:3 as well as other pyridylglycols. I have found that if I heat, for example, 2-propan 3-olpyridine-N-oxide with an organic acid anhydride and hydrolyze the resulting product, I obtain in good yield a pyridylglycol, such, for example, as 1-( Z-pyridyDpropandiol 1 :3.

A convenient way of carrying out my invention is illustrated in the following specific examples. The alkanol Pretti s s a e n w tem erat he wit s n 159 pounds of 2-propan-3-.olpyridine-N-oxide. The addi- 2,743,277 Batented Apr. 24, 1956 2 ject of my co-pending patent application Serial No. 435,689 filed even date herewith.

The alkanolpyridine-N- oxides may be prepared by oxidizing at about 75-85? C. an acetic acid solution of an alkanolpyridine acetate with hydrogen peroxide, dis; tilling off the water and most of the acetic acid, refluxing the distillation residue with an excess of aqueous caustic soda solution, extracting the alkanolpyridine-N-oxide from the caustic solution with benzene and then evaporating the benzene to obtainthe alkanolpyridine N- oxide.

EXAMPLE 1 1-(2-pyridyl)pr0pandiol 1:3

-onzomorr \N CH2CH2CH2OH i 0 To 250-300 pounds of refluxing acetic anhydride add i tioh should be made in small portions as considerablelieat evolved by the reaction of the 2-ptopanolpyridine-N oxide with the acetic anhydride. When all of the N-oxide has been added, the resulting solution is main tained at refluxing temperature for about two hours.

Then the solution is subjected to vacuum distillation to 7 remove the unreacted acetic anhydride. To the residue remaining after the. acetic anhydride has, been removed, there is added about '750l,000 parts of an aqueous caustic soda solution. The resulting mixture is heated at. reflux conditions for about four to six hours. Then the mixture is cooled and thoroughly extracted with about 350 to 500 parts of diethyl ether. The ether extract contains the 1-(2-pyridyl)propandiol 1:3 which was found during the preceding reaction. The ether solution is dried and then the ether is removedby vacuum distillation. Thererernains an oily residue of l-( 2-pyridyl)propandiol 1:3.

EXAMPLE 2 I-(Z-PyI'idyDEIhGILdI QI 1:2

carol-1203a N l O The process of Example 1 is repeated save that pounds of Z-ethan-Z-olpyridine-N-oxide are used instead of the pounds of 2-propan-3-olpyridine-N-oxide used in Example 1. The product formed is l-(2-pyridyl) ethandiol 1:2.

EXAMPLE 3 I (4-pyridyl) propandiol 1:3

One convenient way of recovering the 1-(4-pyridyl)- propandiol 1:3 is as follows: The acetic anhydride is removed by distillation under vacuum. To the residue remaining after the acetic anhydride is removed, is added about 750 pounds of a aqueous caustic soda solution.

The resulting solution is heated at-i'eflux conditions for about four to six hours. The solution is concentrated by evaporating off the water under vacuum. The residue is then extracted with about 500 pounds of hot xylene. The xylene extract, which contains the l-(4-pyridyl)- propandiol 1:3, is subjected to vacuum distillation to remove the xylene. The residue is the 1-(4-pyridyl)- propandiol- 1:3. The yield of this glycol is not as high as was that of the 1(2-pyridyl)propandiol 1:3.

EXAMPLE 4 1 -(2-pyridyl) butandz'ol 1:4

it v The process of Examples 1 and 3 is repeated save that 2-butan-4-olpyridine-N-oxide is used in place of the 2-propan-3-olpyridine-N-oxide of Example 1 and of the 4-propan-3-olpyridine-N-oxide of Example 3. The prodnot recovered is 1-(2-pyridyl)butandiol 1:4.

EXAMPLE 5 1-(2-5-ethylpyridyl) ethandiol 1 :2

can,-

H ornornon iz-ongon H v o I pyridine, I cite the following:

EXAMPLE 6 i N/CH2CH9CH2OH -ooiznonlon A solution of 150 pounds of 2-propan-3-olpyridine and about 280 parts of glacial acetic acid is heated to a reflux temperature for about four hours. The solution is then cooled to a temperature of about 75 C. and 210 parts of hydrogen peroxide (35% H202) is added. The hydrogen peroxide is preferably added in small portions during a four hour period. The temperature of the solution is maintained at 75 C. during the addition of the hydrogen peroxide. After all of the hydrogen peroxide has been added the solution is maintained at the elevated temperature for an additional 16-20 hours. Then the solution is heated to about 95 C. and about 18 parts of paraformaldehyde is added. The paraformaldehyde is added to destroy any unreacted peroxide. The peroxide free solution is concentrated by distilling off the water and most of the acetic acid. The concentration is carried out under vacuum (30-75 mm. Hg) and is discontinued when no more distillate is obtained and the temperature of the liquid reaches about 100' C. The concentrated reaction mixture is added, in small portions, to 600 parts of hot (95100 C.) acetic anhydride. The resulting solution is maintained at 95-l00 C. for about two hours. The resultant 1-(2-pyridyl)propandiol 1:3 is recovered from the acetic anhydride solution in any suitable manner, as for example, by the procedure of Example 1 above.

I claim as my invention:

1. The process of preparing compounds of the class consisting of Z-pyridylglycols and 4-pyridylglycols having the following general formulae:

eral formulae:

L CHz-(C H1) "OH and UHz-(CHnhOH N l o wheren is 1 to 3 and R and R are selected from the class consisting of hydrogen, methyl and ethyl and recovering the pyridylglycol from the reaction mixture.

2. The process of preparing 1-(2-pyridyl)propandiol 1:3 which comprises reacting 2-propan-3-olpyridine-N- oxide with acetic anhydride and recovering the 1-(2-pyridy1)propandiol 1:3.

3. The process of preparing 1-(2-pyridyl)ethandiol 1:2 which comprises reacting 2-ethan-2-olpyridine-N- oxide with acetic anhydride and recovering l-(2-pyridyl)- ethandiol 1:2.

4. The process of preparing 1-(4-pyridyl)propandiol 1:3 which comprises reacting 4-propan-3-olpyridine-N- oxide with acetic anhydride and recovering the 1-(4-pyridyl)propandiol 1:3.

5. The process of preparing 1-(4-pyridyl)ethandiol 1:2 which comprises reacting 4-ethan-2-olpyridine-N- oxide with acetic anhydride and recovering the 1-(4-pyridyl)ethandiol 1:2.

6. Compounds of the class consisting of 2-pyridylgly- 6 and R are selected from the class consisting of hydrogen, methyl and ethyl.

7. The compound 1-(2-pyridyl)propandiol 1:3.

cols end 4-pyridylglycols having the following general where n is 1 to 3 and R formulae:

R R 8. The compound I-(Z-pyridyDethandiol 1:2. 5 9. The compound I-(Z-pyridyDbutandiol 1:4. N (f-(CHMOH 10. The compound 1-(4-pyridyl)propandiol 1:3. and OH References Cited in the file of this patent OH 10 UNITED STATES PATENTS 2,512,660 Mahan June 27, 1950 

6. COMPOUND OF THE CLASS CONSISTING OF 2-PYRIDYLGLYCOLS AND 4-PYRIDYLGLYCOLS HAVING THE FOLLOWING GENERAL FORMULA: 